Figure 5: Angular dependence of the -value of , , and evaluated at , 50, and 60 K, respectively, when a static magnetic field is rotated in the plane. The dashed lines indicate the calculated variation (equation C1 in the appendix) of the -values of the two magnetically inequivalent sites. A view along the molecular axis is sketched in the lower panel. Below the charge distribution on the dimer becomes imbalanced (indicated by the different grey shades). The distinct coupling to the anions (green circles) modifies the electronic wavefunction causing the g-tensor to rotate in opposite directions, as depicted by the brown arrows. The transfer integrals and differ by about 40% at room temperature.